1. Field of the Invention
This invention relates to autostereoscopic display devices for use in television, computer graphic, and the like viewing applications. It also relates to ultrasonic echo ranging devices designed to determine the location of a person or a person's head.
2. Prior Art
U.S. Pat. No. 4,717,949 describes an autostereoscopic display using stationary light emitting lines in combination with an image generating light valve to produce stereoscopic images that can be seen without the use of glasses or optical devices by the observer. Like most such autostereoscopic devices, this one produces images that can only be seen within certain narrow viewing zones spaced in front of the device. In order to view the images, the observer must keep his or her eyes positioned within two of several adjacent 2.5 inches (approximately 63 millimeters [mm]) wide areas in front of the display.
It is therefore an object of this invention to provide a device which can sense the position of a single observer's head, and position the optics within the stereo display so that the central viewing zone is automatically aligned on the observers head, and remains aligned on it as the person moves their head back and forth and sideways.
A further object of this invention is to provide a device that allows an observer a wide latitude for head movement and body position when using an autostereoscopic display.
Another object of this invention is to provide a device which uses head position data to alter the operation of a software program, so that the program always displays images on a screen with a perspective appropriate to the observer's eye positions.
Yet another object of this invention is to achieve the above objectives without the use of moving parts within the display.